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1/*
2 * linux/ipc/util.c
3 * Copyright (C) 1992 Krishna Balasubramanian
4 *
5 * Sep 1997 - Call suser() last after "normal" permission checks so we
6 * get BSD style process accounting right.
7 * Occurs in several places in the IPC code.
8 * Chris Evans, <chris@ferret.lmh.ox.ac.uk>
9 * Nov 1999 - ipc helper functions, unified SMP locking
10 * Manfred Spraul <manfred@colorfullife.com>
11 * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
12 * Mingming Cao <cmm@us.ibm.com>
13 * Mar 2006 - support for audit of ipc object properties
14 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
15 * Jun 2006 - namespaces ssupport
16 * OpenVZ, SWsoft Inc.
17 * Pavel Emelianov <xemul@openvz.org>
18 *
19 * General sysv ipc locking scheme:
20 * rcu_read_lock()
21 * obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
22 * tree.
23 * - perform initial checks (capabilities, auditing and permission,
24 * etc).
25 * - perform read-only operations, such as STAT, INFO commands.
26 * acquire the ipc lock (kern_ipc_perm.lock) through
27 * ipc_lock_object()
28 * - perform data updates, such as SET, RMID commands and
29 * mechanism-specific operations (semop/semtimedop,
30 * msgsnd/msgrcv, shmat/shmdt).
31 * drop the ipc lock, through ipc_unlock_object().
32 * rcu_read_unlock()
33 *
34 * The ids->rwsem must be taken when:
35 * - creating, removing and iterating the existing entries in ipc
36 * identifier sets.
37 * - iterating through files under /proc/sysvipc/
38 *
39 * Note that sems have a special fast path that avoids kern_ipc_perm.lock -
40 * see sem_lock().
41 */
42
43#include <linux/mm.h>
44#include <linux/shm.h>
45#include <linux/init.h>
46#include <linux/msg.h>
47#include <linux/vmalloc.h>
48#include <linux/slab.h>
49#include <linux/notifier.h>
50#include <linux/capability.h>
51#include <linux/highuid.h>
52#include <linux/security.h>
53#include <linux/rcupdate.h>
54#include <linux/workqueue.h>
55#include <linux/seq_file.h>
56#include <linux/proc_fs.h>
57#include <linux/audit.h>
58#include <linux/nsproxy.h>
59#include <linux/rwsem.h>
60#include <linux/memory.h>
61#include <linux/ipc_namespace.h>
62
63#include <asm/unistd.h>
64
65#include "util.h"
66
67struct ipc_proc_iface {
68 const char *path;
69 const char *header;
70 int ids;
71 int (*show)(struct seq_file *, void *);
72};
73
74/**
75 * ipc_init - initialise ipc subsystem
76 *
77 * The various sysv ipc resources (semaphores, messages and shared
78 * memory) are initialised.
79 *
80 * A callback routine is registered into the memory hotplug notifier
81 * chain: since msgmni scales to lowmem this callback routine will be
82 * called upon successful memory add / remove to recompute msmgni.
83 */
84static int __init ipc_init(void)
85{
86 sem_init();
87 msg_init();
88 shm_init();
89 return 0;
90}
91device_initcall(ipc_init);
92
93/**
94 * ipc_init_ids - initialise ipc identifiers
95 * @ids: ipc identifier set
96 *
97 * Set up the sequence range to use for the ipc identifier range (limited
98 * below IPCMNI) then initialise the ids idr.
99 */
100void ipc_init_ids(struct ipc_ids *ids)
101{
102 ids->in_use = 0;
103 ids->seq = 0;
104 ids->next_id = -1;
105 init_rwsem(&ids->rwsem);
106 idr_init(&ids->ipcs_idr);
107}
108
109#ifdef CONFIG_PROC_FS
110static const struct file_operations sysvipc_proc_fops;
111/**
112 * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface.
113 * @path: Path in procfs
114 * @header: Banner to be printed at the beginning of the file.
115 * @ids: ipc id table to iterate.
116 * @show: show routine.
117 */
118void __init ipc_init_proc_interface(const char *path, const char *header,
119 int ids, int (*show)(struct seq_file *, void *))
120{
121 struct proc_dir_entry *pde;
122 struct ipc_proc_iface *iface;
123
124 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
125 if (!iface)
126 return;
127 iface->path = path;
128 iface->header = header;
129 iface->ids = ids;
130 iface->show = show;
131
132 pde = proc_create_data(path,
133 S_IRUGO, /* world readable */
134 NULL, /* parent dir */
135 &sysvipc_proc_fops,
136 iface);
137 if (!pde)
138 kfree(iface);
139}
140#endif
141
142/**
143 * ipc_findkey - find a key in an ipc identifier set
144 * @ids: ipc identifier set
145 * @key: key to find
146 *
147 * Returns the locked pointer to the ipc structure if found or NULL
148 * otherwise. If key is found ipc points to the owning ipc structure
149 *
150 * Called with ipc_ids.rwsem held.
151 */
152static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
153{
154 struct kern_ipc_perm *ipc;
155 int next_id;
156 int total;
157
158 for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
159 ipc = idr_find(&ids->ipcs_idr, next_id);
160
161 if (ipc == NULL)
162 continue;
163
164 if (ipc->key != key) {
165 total++;
166 continue;
167 }
168
169 rcu_read_lock();
170 ipc_lock_object(ipc);
171 return ipc;
172 }
173
174 return NULL;
175}
176
177/**
178 * ipc_get_maxid - get the last assigned id
179 * @ids: ipc identifier set
180 *
181 * Called with ipc_ids.rwsem held.
182 */
183int ipc_get_maxid(struct ipc_ids *ids)
184{
185 struct kern_ipc_perm *ipc;
186 int max_id = -1;
187 int total, id;
188
189 if (ids->in_use == 0)
190 return -1;
191
192 if (ids->in_use == IPCMNI)
193 return IPCMNI - 1;
194
195 /* Look for the last assigned id */
196 total = 0;
197 for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
198 ipc = idr_find(&ids->ipcs_idr, id);
199 if (ipc != NULL) {
200 max_id = id;
201 total++;
202 }
203 }
204 return max_id;
205}
206
207/**
208 * ipc_addid - add an ipc identifier
209 * @ids: ipc identifier set
210 * @new: new ipc permission set
211 * @size: limit for the number of used ids
212 *
213 * Add an entry 'new' to the ipc ids idr. The permissions object is
214 * initialised and the first free entry is set up and the id assigned
215 * is returned. The 'new' entry is returned in a locked state on success.
216 * On failure the entry is not locked and a negative err-code is returned.
217 *
218 * Called with writer ipc_ids.rwsem held.
219 */
220int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
221{
222 kuid_t euid;
223 kgid_t egid;
224 int id;
225 int next_id = ids->next_id;
226
227 if (size > IPCMNI)
228 size = IPCMNI;
229
230 if (ids->in_use >= size)
231 return -ENOSPC;
232
233 idr_preload(GFP_KERNEL);
234
235 spin_lock_init(&new->lock);
236 new->deleted = false;
237 rcu_read_lock();
238 spin_lock(&new->lock);
239
240 current_euid_egid(&euid, &egid);
241 new->cuid = new->uid = euid;
242 new->gid = new->cgid = egid;
243
244 id = idr_alloc(&ids->ipcs_idr, new,
245 (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
246 GFP_NOWAIT);
247 idr_preload_end();
248 if (id < 0) {
249 spin_unlock(&new->lock);
250 rcu_read_unlock();
251 return id;
252 }
253
254 ids->in_use++;
255
256 if (next_id < 0) {
257 new->seq = ids->seq++;
258 if (ids->seq > IPCID_SEQ_MAX)
259 ids->seq = 0;
260 } else {
261 new->seq = ipcid_to_seqx(next_id);
262 ids->next_id = -1;
263 }
264
265 new->id = ipc_buildid(id, new->seq);
266 return id;
267}
268
269/**
270 * ipcget_new - create a new ipc object
271 * @ns: ipc namespace
272 * @ids: ipc identifier set
273 * @ops: the actual creation routine to call
274 * @params: its parameters
275 *
276 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
277 * when the key is IPC_PRIVATE.
278 */
279static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
280 const struct ipc_ops *ops, struct ipc_params *params)
281{
282 int err;
283
284 down_write(&ids->rwsem);
285 err = ops->getnew(ns, params);
286 up_write(&ids->rwsem);
287 return err;
288}
289
290/**
291 * ipc_check_perms - check security and permissions for an ipc object
292 * @ns: ipc namespace
293 * @ipcp: ipc permission set
294 * @ops: the actual security routine to call
295 * @params: its parameters
296 *
297 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
298 * when the key is not IPC_PRIVATE and that key already exists in the
299 * ds IDR.
300 *
301 * On success, the ipc id is returned.
302 *
303 * It is called with ipc_ids.rwsem and ipcp->lock held.
304 */
305static int ipc_check_perms(struct ipc_namespace *ns,
306 struct kern_ipc_perm *ipcp,
307 const struct ipc_ops *ops,
308 struct ipc_params *params)
309{
310 int err;
311
312 if (ipcperms(ns, ipcp, params->flg))
313 err = -EACCES;
314 else {
315 err = ops->associate(ipcp, params->flg);
316 if (!err)
317 err = ipcp->id;
318 }
319
320 return err;
321}
322
323/**
324 * ipcget_public - get an ipc object or create a new one
325 * @ns: ipc namespace
326 * @ids: ipc identifier set
327 * @ops: the actual creation routine to call
328 * @params: its parameters
329 *
330 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
331 * when the key is not IPC_PRIVATE.
332 * It adds a new entry if the key is not found and does some permission
333 * / security checkings if the key is found.
334 *
335 * On success, the ipc id is returned.
336 */
337static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
338 const struct ipc_ops *ops, struct ipc_params *params)
339{
340 struct kern_ipc_perm *ipcp;
341 int flg = params->flg;
342 int err;
343
344 /*
345 * Take the lock as a writer since we are potentially going to add
346 * a new entry + read locks are not "upgradable"
347 */
348 down_write(&ids->rwsem);
349 ipcp = ipc_findkey(ids, params->key);
350 if (ipcp == NULL) {
351 /* key not used */
352 if (!(flg & IPC_CREAT))
353 err = -ENOENT;
354 else
355 err = ops->getnew(ns, params);
356 } else {
357 /* ipc object has been locked by ipc_findkey() */
358
359 if (flg & IPC_CREAT && flg & IPC_EXCL)
360 err = -EEXIST;
361 else {
362 err = 0;
363 if (ops->more_checks)
364 err = ops->more_checks(ipcp, params);
365 if (!err)
366 /*
367 * ipc_check_perms returns the IPC id on
368 * success
369 */
370 err = ipc_check_perms(ns, ipcp, ops, params);
371 }
372 ipc_unlock(ipcp);
373 }
374 up_write(&ids->rwsem);
375
376 return err;
377}
378
379
380/**
381 * ipc_rmid - remove an ipc identifier
382 * @ids: ipc identifier set
383 * @ipcp: ipc perm structure containing the identifier to remove
384 *
385 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
386 * before this function is called, and remain locked on the exit.
387 */
388void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
389{
390 int lid = ipcid_to_idx(ipcp->id);
391
392 idr_remove(&ids->ipcs_idr, lid);
393 ids->in_use--;
394 ipcp->deleted = true;
395}
396
397/**
398 * ipc_alloc - allocate ipc space
399 * @size: size desired
400 *
401 * Allocate memory from the appropriate pools and return a pointer to it.
402 * NULL is returned if the allocation fails
403 */
404void *ipc_alloc(int size)
405{
406 void *out;
407 if (size > PAGE_SIZE)
408 out = vmalloc(size);
409 else
410 out = kmalloc(size, GFP_KERNEL);
411 return out;
412}
413
414/**
415 * ipc_free - free ipc space
416 * @ptr: pointer returned by ipc_alloc
417 *
418 * Free a block created with ipc_alloc().
419 */
420void ipc_free(void *ptr)
421{
422 kvfree(ptr);
423}
424
425/**
426 * ipc_rcu_alloc - allocate ipc and rcu space
427 * @size: size desired
428 *
429 * Allocate memory for the rcu header structure + the object.
430 * Returns the pointer to the object or NULL upon failure.
431 */
432void *ipc_rcu_alloc(int size)
433{
434 /*
435 * We prepend the allocation with the rcu struct
436 */
437 struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size);
438 if (unlikely(!out))
439 return NULL;
440 atomic_set(&out->refcount, 1);
441 return out + 1;
442}
443
444int ipc_rcu_getref(void *ptr)
445{
446 struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
447
448 return atomic_inc_not_zero(&p->refcount);
449}
450
451void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head))
452{
453 struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
454
455 if (!atomic_dec_and_test(&p->refcount))
456 return;
457
458 call_rcu(&p->rcu, func);
459}
460
461void ipc_rcu_free(struct rcu_head *head)
462{
463 struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
464
465 kvfree(p);
466}
467
468/**
469 * ipcperms - check ipc permissions
470 * @ns: ipc namespace
471 * @ipcp: ipc permission set
472 * @flag: desired permission set
473 *
474 * Check user, group, other permissions for access
475 * to ipc resources. return 0 if allowed
476 *
477 * @flag will most probably be 0 or S_...UGO from <linux/stat.h>
478 */
479int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
480{
481 kuid_t euid = current_euid();
482 int requested_mode, granted_mode;
483
484 audit_ipc_obj(ipcp);
485 requested_mode = (flag >> 6) | (flag >> 3) | flag;
486 granted_mode = ipcp->mode;
487 if (uid_eq(euid, ipcp->cuid) ||
488 uid_eq(euid, ipcp->uid))
489 granted_mode >>= 6;
490 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
491 granted_mode >>= 3;
492 /* is there some bit set in requested_mode but not in granted_mode? */
493 if ((requested_mode & ~granted_mode & 0007) &&
494 !ns_capable(ns->user_ns, CAP_IPC_OWNER))
495 return -1;
496
497 return security_ipc_permission(ipcp, flag);
498}
499
500/*
501 * Functions to convert between the kern_ipc_perm structure and the
502 * old/new ipc_perm structures
503 */
504
505/**
506 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
507 * @in: kernel permissions
508 * @out: new style ipc permissions
509 *
510 * Turn the kernel object @in into a set of permissions descriptions
511 * for returning to userspace (@out).
512 */
513void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
514{
515 out->key = in->key;
516 out->uid = from_kuid_munged(current_user_ns(), in->uid);
517 out->gid = from_kgid_munged(current_user_ns(), in->gid);
518 out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
519 out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
520 out->mode = in->mode;
521 out->seq = in->seq;
522}
523
524/**
525 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
526 * @in: new style ipc permissions
527 * @out: old style ipc permissions
528 *
529 * Turn the new style permissions object @in into a compatibility
530 * object and store it into the @out pointer.
531 */
532void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
533{
534 out->key = in->key;
535 SET_UID(out->uid, in->uid);
536 SET_GID(out->gid, in->gid);
537 SET_UID(out->cuid, in->cuid);
538 SET_GID(out->cgid, in->cgid);
539 out->mode = in->mode;
540 out->seq = in->seq;
541}
542
543/**
544 * ipc_obtain_object
545 * @ids: ipc identifier set
546 * @id: ipc id to look for
547 *
548 * Look for an id in the ipc ids idr and return associated ipc object.
549 *
550 * Call inside the RCU critical section.
551 * The ipc object is *not* locked on exit.
552 */
553struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
554{
555 struct kern_ipc_perm *out;
556 int lid = ipcid_to_idx(id);
557
558 out = idr_find(&ids->ipcs_idr, lid);
559 if (!out)
560 return ERR_PTR(-EINVAL);
561
562 return out;
563}
564
565/**
566 * ipc_lock - lock an ipc structure without rwsem held
567 * @ids: ipc identifier set
568 * @id: ipc id to look for
569 *
570 * Look for an id in the ipc ids idr and lock the associated ipc object.
571 *
572 * The ipc object is locked on successful exit.
573 */
574struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
575{
576 struct kern_ipc_perm *out;
577
578 rcu_read_lock();
579 out = ipc_obtain_object_idr(ids, id);
580 if (IS_ERR(out))
581 goto err;
582
583 spin_lock(&out->lock);
584
585 /*
586 * ipc_rmid() may have already freed the ID while ipc_lock()
587 * was spinning: here verify that the structure is still valid.
588 * Upon races with RMID, return -EIDRM, thus indicating that
589 * the ID points to a removed identifier.
590 */
591 if (ipc_valid_object(out))
592 return out;
593
594 spin_unlock(&out->lock);
595 out = ERR_PTR(-EIDRM);
596err:
597 rcu_read_unlock();
598 return out;
599}
600
601/**
602 * ipc_obtain_object_check
603 * @ids: ipc identifier set
604 * @id: ipc id to look for
605 *
606 * Similar to ipc_obtain_object_idr() but also checks
607 * the ipc object reference counter.
608 *
609 * Call inside the RCU critical section.
610 * The ipc object is *not* locked on exit.
611 */
612struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
613{
614 struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
615
616 if (IS_ERR(out))
617 goto out;
618
619 if (ipc_checkid(out, id))
620 return ERR_PTR(-EINVAL);
621out:
622 return out;
623}
624
625/**
626 * ipcget - Common sys_*get() code
627 * @ns: namespace
628 * @ids: ipc identifier set
629 * @ops: operations to be called on ipc object creation, permission checks
630 * and further checks
631 * @params: the parameters needed by the previous operations.
632 *
633 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
634 */
635int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
636 const struct ipc_ops *ops, struct ipc_params *params)
637{
638 if (params->key == IPC_PRIVATE)
639 return ipcget_new(ns, ids, ops, params);
640 else
641 return ipcget_public(ns, ids, ops, params);
642}
643
644/**
645 * ipc_update_perm - update the permissions of an ipc object
646 * @in: the permission given as input.
647 * @out: the permission of the ipc to set.
648 */
649int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
650{
651 kuid_t uid = make_kuid(current_user_ns(), in->uid);
652 kgid_t gid = make_kgid(current_user_ns(), in->gid);
653 if (!uid_valid(uid) || !gid_valid(gid))
654 return -EINVAL;
655
656 out->uid = uid;
657 out->gid = gid;
658 out->mode = (out->mode & ~S_IRWXUGO)
659 | (in->mode & S_IRWXUGO);
660
661 return 0;
662}
663
664/**
665 * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
666 * @ns: ipc namespace
667 * @ids: the table of ids where to look for the ipc
668 * @id: the id of the ipc to retrieve
669 * @cmd: the cmd to check
670 * @perm: the permission to set
671 * @extra_perm: one extra permission parameter used by msq
672 *
673 * This function does some common audit and permissions check for some IPC_XXX
674 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
675 * It must be called without any lock held and
676 * - retrieves the ipc with the given id in the given table.
677 * - performs some audit and permission check, depending on the given cmd
678 * - returns a pointer to the ipc object or otherwise, the corresponding error.
679 *
680 * Call holding the both the rwsem and the rcu read lock.
681 */
682struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
683 struct ipc_ids *ids, int id, int cmd,
684 struct ipc64_perm *perm, int extra_perm)
685{
686 kuid_t euid;
687 int err = -EPERM;
688 struct kern_ipc_perm *ipcp;
689
690 ipcp = ipc_obtain_object_check(ids, id);
691 if (IS_ERR(ipcp)) {
692 err = PTR_ERR(ipcp);
693 goto err;
694 }
695
696 audit_ipc_obj(ipcp);
697 if (cmd == IPC_SET)
698 audit_ipc_set_perm(extra_perm, perm->uid,
699 perm->gid, perm->mode);
700
701 euid = current_euid();
702 if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
703 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
704 return ipcp; /* successful lookup */
705err:
706 return ERR_PTR(err);
707}
708
709#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
710
711
712/**
713 * ipc_parse_version - ipc call version
714 * @cmd: pointer to command
715 *
716 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
717 * The @cmd value is turned from an encoding command and version into
718 * just the command code.
719 */
720int ipc_parse_version(int *cmd)
721{
722 if (*cmd & IPC_64) {
723 *cmd ^= IPC_64;
724 return IPC_64;
725 } else {
726 return IPC_OLD;
727 }
728}
729
730#endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
731
732#ifdef CONFIG_PROC_FS
733struct ipc_proc_iter {
734 struct ipc_namespace *ns;
735 struct ipc_proc_iface *iface;
736};
737
738/*
739 * This routine locks the ipc structure found at least at position pos.
740 */
741static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
742 loff_t *new_pos)
743{
744 struct kern_ipc_perm *ipc;
745 int total, id;
746
747 total = 0;
748 for (id = 0; id < pos && total < ids->in_use; id++) {
749 ipc = idr_find(&ids->ipcs_idr, id);
750 if (ipc != NULL)
751 total++;
752 }
753
754 if (total >= ids->in_use)
755 return NULL;
756
757 for (; pos < IPCMNI; pos++) {
758 ipc = idr_find(&ids->ipcs_idr, pos);
759 if (ipc != NULL) {
760 *new_pos = pos + 1;
761 rcu_read_lock();
762 ipc_lock_object(ipc);
763 return ipc;
764 }
765 }
766
767 /* Out of range - return NULL to terminate iteration */
768 return NULL;
769}
770
771static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
772{
773 struct ipc_proc_iter *iter = s->private;
774 struct ipc_proc_iface *iface = iter->iface;
775 struct kern_ipc_perm *ipc = it;
776
777 /* If we had an ipc id locked before, unlock it */
778 if (ipc && ipc != SEQ_START_TOKEN)
779 ipc_unlock(ipc);
780
781 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
782}
783
784/*
785 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
786 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
787 */
788static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
789{
790 struct ipc_proc_iter *iter = s->private;
791 struct ipc_proc_iface *iface = iter->iface;
792 struct ipc_ids *ids;
793
794 ids = &iter->ns->ids[iface->ids];
795
796 /*
797 * Take the lock - this will be released by the corresponding
798 * call to stop().
799 */
800 down_read(&ids->rwsem);
801
802 /* pos < 0 is invalid */
803 if (*pos < 0)
804 return NULL;
805
806 /* pos == 0 means header */
807 if (*pos == 0)
808 return SEQ_START_TOKEN;
809
810 /* Find the (pos-1)th ipc */
811 return sysvipc_find_ipc(ids, *pos - 1, pos);
812}
813
814static void sysvipc_proc_stop(struct seq_file *s, void *it)
815{
816 struct kern_ipc_perm *ipc = it;
817 struct ipc_proc_iter *iter = s->private;
818 struct ipc_proc_iface *iface = iter->iface;
819 struct ipc_ids *ids;
820
821 /* If we had a locked structure, release it */
822 if (ipc && ipc != SEQ_START_TOKEN)
823 ipc_unlock(ipc);
824
825 ids = &iter->ns->ids[iface->ids];
826 /* Release the lock we took in start() */
827 up_read(&ids->rwsem);
828}
829
830static int sysvipc_proc_show(struct seq_file *s, void *it)
831{
832 struct ipc_proc_iter *iter = s->private;
833 struct ipc_proc_iface *iface = iter->iface;
834
835 if (it == SEQ_START_TOKEN) {
836 seq_puts(s, iface->header);
837 return 0;
838 }
839
840 return iface->show(s, it);
841}
842
843static const struct seq_operations sysvipc_proc_seqops = {
844 .start = sysvipc_proc_start,
845 .stop = sysvipc_proc_stop,
846 .next = sysvipc_proc_next,
847 .show = sysvipc_proc_show,
848};
849
850static int sysvipc_proc_open(struct inode *inode, struct file *file)
851{
852 struct ipc_proc_iter *iter;
853
854 iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
855 if (!iter)
856 return -ENOMEM;
857
858 iter->iface = PDE_DATA(inode);
859 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
860
861 return 0;
862}
863
864static int sysvipc_proc_release(struct inode *inode, struct file *file)
865{
866 struct seq_file *seq = file->private_data;
867 struct ipc_proc_iter *iter = seq->private;
868 put_ipc_ns(iter->ns);
869 return seq_release_private(inode, file);
870}
871
872static const struct file_operations sysvipc_proc_fops = {
873 .open = sysvipc_proc_open,
874 .read = seq_read,
875 .llseek = seq_lseek,
876 .release = sysvipc_proc_release,
877};
878#endif /* CONFIG_PROC_FS */
1/*
2 * linux/ipc/util.c
3 * Copyright (C) 1992 Krishna Balasubramanian
4 *
5 * Sep 1997 - Call suser() last after "normal" permission checks so we
6 * get BSD style process accounting right.
7 * Occurs in several places in the IPC code.
8 * Chris Evans, <chris@ferret.lmh.ox.ac.uk>
9 * Nov 1999 - ipc helper functions, unified SMP locking
10 * Manfred Spraul <manfred@colorfullife.com>
11 * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
12 * Mingming Cao <cmm@us.ibm.com>
13 * Mar 2006 - support for audit of ipc object properties
14 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
15 * Jun 2006 - namespaces ssupport
16 * OpenVZ, SWsoft Inc.
17 * Pavel Emelianov <xemul@openvz.org>
18 *
19 * General sysv ipc locking scheme:
20 * rcu_read_lock()
21 * obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
22 * tree.
23 * - perform initial checks (capabilities, auditing and permission,
24 * etc).
25 * - perform read-only operations, such as STAT, INFO commands.
26 * acquire the ipc lock (kern_ipc_perm.lock) through
27 * ipc_lock_object()
28 * - perform data updates, such as SET, RMID commands and
29 * mechanism-specific operations (semop/semtimedop,
30 * msgsnd/msgrcv, shmat/shmdt).
31 * drop the ipc lock, through ipc_unlock_object().
32 * rcu_read_unlock()
33 *
34 * The ids->rwsem must be taken when:
35 * - creating, removing and iterating the existing entries in ipc
36 * identifier sets.
37 * - iterating through files under /proc/sysvipc/
38 *
39 * Note that sems have a special fast path that avoids kern_ipc_perm.lock -
40 * see sem_lock().
41 */
42
43#include <linux/mm.h>
44#include <linux/shm.h>
45#include <linux/init.h>
46#include <linux/msg.h>
47#include <linux/vmalloc.h>
48#include <linux/slab.h>
49#include <linux/notifier.h>
50#include <linux/capability.h>
51#include <linux/highuid.h>
52#include <linux/security.h>
53#include <linux/rcupdate.h>
54#include <linux/workqueue.h>
55#include <linux/seq_file.h>
56#include <linux/proc_fs.h>
57#include <linux/audit.h>
58#include <linux/nsproxy.h>
59#include <linux/rwsem.h>
60#include <linux/memory.h>
61#include <linux/ipc_namespace.h>
62
63#include <asm/unistd.h>
64
65#include "util.h"
66
67struct ipc_proc_iface {
68 const char *path;
69 const char *header;
70 int ids;
71 int (*show)(struct seq_file *, void *);
72};
73
74static void ipc_memory_notifier(struct work_struct *work)
75{
76 ipcns_notify(IPCNS_MEMCHANGED);
77}
78
79static int ipc_memory_callback(struct notifier_block *self,
80 unsigned long action, void *arg)
81{
82 static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
83
84 switch (action) {
85 case MEM_ONLINE: /* memory successfully brought online */
86 case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */
87 /*
88 * This is done by invoking the ipcns notifier chain with the
89 * IPC_MEMCHANGED event.
90 * In order not to keep the lock on the hotplug memory chain
91 * for too long, queue a work item that will, when waken up,
92 * activate the ipcns notification chain.
93 */
94 schedule_work(&ipc_memory_wq);
95 break;
96 case MEM_GOING_ONLINE:
97 case MEM_GOING_OFFLINE:
98 case MEM_CANCEL_ONLINE:
99 case MEM_CANCEL_OFFLINE:
100 default:
101 break;
102 }
103
104 return NOTIFY_OK;
105}
106
107static struct notifier_block ipc_memory_nb = {
108 .notifier_call = ipc_memory_callback,
109 .priority = IPC_CALLBACK_PRI,
110};
111
112/**
113 * ipc_init - initialise ipc subsystem
114 *
115 * The various sysv ipc resources (semaphores, messages and shared
116 * memory) are initialised.
117 *
118 * A callback routine is registered into the memory hotplug notifier
119 * chain: since msgmni scales to lowmem this callback routine will be
120 * called upon successful memory add / remove to recompute msmgni.
121 */
122static int __init ipc_init(void)
123{
124 sem_init();
125 msg_init();
126 shm_init();
127 register_hotmemory_notifier(&ipc_memory_nb);
128 register_ipcns_notifier(&init_ipc_ns);
129 return 0;
130}
131device_initcall(ipc_init);
132
133/**
134 * ipc_init_ids - initialise ipc identifiers
135 * @ids: ipc identifier set
136 *
137 * Set up the sequence range to use for the ipc identifier range (limited
138 * below IPCMNI) then initialise the ids idr.
139 */
140void ipc_init_ids(struct ipc_ids *ids)
141{
142 ids->in_use = 0;
143 ids->seq = 0;
144 ids->next_id = -1;
145 init_rwsem(&ids->rwsem);
146 idr_init(&ids->ipcs_idr);
147}
148
149#ifdef CONFIG_PROC_FS
150static const struct file_operations sysvipc_proc_fops;
151/**
152 * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface.
153 * @path: Path in procfs
154 * @header: Banner to be printed at the beginning of the file.
155 * @ids: ipc id table to iterate.
156 * @show: show routine.
157 */
158void __init ipc_init_proc_interface(const char *path, const char *header,
159 int ids, int (*show)(struct seq_file *, void *))
160{
161 struct proc_dir_entry *pde;
162 struct ipc_proc_iface *iface;
163
164 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
165 if (!iface)
166 return;
167 iface->path = path;
168 iface->header = header;
169 iface->ids = ids;
170 iface->show = show;
171
172 pde = proc_create_data(path,
173 S_IRUGO, /* world readable */
174 NULL, /* parent dir */
175 &sysvipc_proc_fops,
176 iface);
177 if (!pde)
178 kfree(iface);
179}
180#endif
181
182/**
183 * ipc_findkey - find a key in an ipc identifier set
184 * @ids: ipc identifier set
185 * @key: key to find
186 *
187 * Returns the locked pointer to the ipc structure if found or NULL
188 * otherwise. If key is found ipc points to the owning ipc structure
189 *
190 * Called with ipc_ids.rwsem held.
191 */
192static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
193{
194 struct kern_ipc_perm *ipc;
195 int next_id;
196 int total;
197
198 for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
199 ipc = idr_find(&ids->ipcs_idr, next_id);
200
201 if (ipc == NULL)
202 continue;
203
204 if (ipc->key != key) {
205 total++;
206 continue;
207 }
208
209 rcu_read_lock();
210 ipc_lock_object(ipc);
211 return ipc;
212 }
213
214 return NULL;
215}
216
217/**
218 * ipc_get_maxid - get the last assigned id
219 * @ids: ipc identifier set
220 *
221 * Called with ipc_ids.rwsem held.
222 */
223int ipc_get_maxid(struct ipc_ids *ids)
224{
225 struct kern_ipc_perm *ipc;
226 int max_id = -1;
227 int total, id;
228
229 if (ids->in_use == 0)
230 return -1;
231
232 if (ids->in_use == IPCMNI)
233 return IPCMNI - 1;
234
235 /* Look for the last assigned id */
236 total = 0;
237 for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
238 ipc = idr_find(&ids->ipcs_idr, id);
239 if (ipc != NULL) {
240 max_id = id;
241 total++;
242 }
243 }
244 return max_id;
245}
246
247/**
248 * ipc_addid - add an ipc identifier
249 * @ids: ipc identifier set
250 * @new: new ipc permission set
251 * @size: limit for the number of used ids
252 *
253 * Add an entry 'new' to the ipc ids idr. The permissions object is
254 * initialised and the first free entry is set up and the id assigned
255 * is returned. The 'new' entry is returned in a locked state on success.
256 * On failure the entry is not locked and a negative err-code is returned.
257 *
258 * Called with writer ipc_ids.rwsem held.
259 */
260int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
261{
262 kuid_t euid;
263 kgid_t egid;
264 int id;
265 int next_id = ids->next_id;
266
267 if (size > IPCMNI)
268 size = IPCMNI;
269
270 if (ids->in_use >= size)
271 return -ENOSPC;
272
273 idr_preload(GFP_KERNEL);
274
275 spin_lock_init(&new->lock);
276 new->deleted = false;
277 rcu_read_lock();
278 spin_lock(&new->lock);
279
280 id = idr_alloc(&ids->ipcs_idr, new,
281 (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
282 GFP_NOWAIT);
283 idr_preload_end();
284 if (id < 0) {
285 spin_unlock(&new->lock);
286 rcu_read_unlock();
287 return id;
288 }
289
290 ids->in_use++;
291
292 current_euid_egid(&euid, &egid);
293 new->cuid = new->uid = euid;
294 new->gid = new->cgid = egid;
295
296 if (next_id < 0) {
297 new->seq = ids->seq++;
298 if (ids->seq > IPCID_SEQ_MAX)
299 ids->seq = 0;
300 } else {
301 new->seq = ipcid_to_seqx(next_id);
302 ids->next_id = -1;
303 }
304
305 new->id = ipc_buildid(id, new->seq);
306 return id;
307}
308
309/**
310 * ipcget_new - create a new ipc object
311 * @ns: ipc namespace
312 * @ids: ipc identifer set
313 * @ops: the actual creation routine to call
314 * @params: its parameters
315 *
316 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
317 * when the key is IPC_PRIVATE.
318 */
319static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
320 struct ipc_ops *ops, struct ipc_params *params)
321{
322 int err;
323
324 down_write(&ids->rwsem);
325 err = ops->getnew(ns, params);
326 up_write(&ids->rwsem);
327 return err;
328}
329
330/**
331 * ipc_check_perms - check security and permissions for an ipc object
332 * @ns: ipc namespace
333 * @ipcp: ipc permission set
334 * @ops: the actual security routine to call
335 * @params: its parameters
336 *
337 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
338 * when the key is not IPC_PRIVATE and that key already exists in the
339 * ds IDR.
340 *
341 * On success, the ipc id is returned.
342 *
343 * It is called with ipc_ids.rwsem and ipcp->lock held.
344 */
345static int ipc_check_perms(struct ipc_namespace *ns,
346 struct kern_ipc_perm *ipcp,
347 struct ipc_ops *ops,
348 struct ipc_params *params)
349{
350 int err;
351
352 if (ipcperms(ns, ipcp, params->flg))
353 err = -EACCES;
354 else {
355 err = ops->associate(ipcp, params->flg);
356 if (!err)
357 err = ipcp->id;
358 }
359
360 return err;
361}
362
363/**
364 * ipcget_public - get an ipc object or create a new one
365 * @ns: ipc namespace
366 * @ids: ipc identifer set
367 * @ops: the actual creation routine to call
368 * @params: its parameters
369 *
370 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
371 * when the key is not IPC_PRIVATE.
372 * It adds a new entry if the key is not found and does some permission
373 * / security checkings if the key is found.
374 *
375 * On success, the ipc id is returned.
376 */
377static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
378 struct ipc_ops *ops, struct ipc_params *params)
379{
380 struct kern_ipc_perm *ipcp;
381 int flg = params->flg;
382 int err;
383
384 /*
385 * Take the lock as a writer since we are potentially going to add
386 * a new entry + read locks are not "upgradable"
387 */
388 down_write(&ids->rwsem);
389 ipcp = ipc_findkey(ids, params->key);
390 if (ipcp == NULL) {
391 /* key not used */
392 if (!(flg & IPC_CREAT))
393 err = -ENOENT;
394 else
395 err = ops->getnew(ns, params);
396 } else {
397 /* ipc object has been locked by ipc_findkey() */
398
399 if (flg & IPC_CREAT && flg & IPC_EXCL)
400 err = -EEXIST;
401 else {
402 err = 0;
403 if (ops->more_checks)
404 err = ops->more_checks(ipcp, params);
405 if (!err)
406 /*
407 * ipc_check_perms returns the IPC id on
408 * success
409 */
410 err = ipc_check_perms(ns, ipcp, ops, params);
411 }
412 ipc_unlock(ipcp);
413 }
414 up_write(&ids->rwsem);
415
416 return err;
417}
418
419
420/**
421 * ipc_rmid - remove an ipc identifier
422 * @ids: ipc identifier set
423 * @ipcp: ipc perm structure containing the identifier to remove
424 *
425 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
426 * before this function is called, and remain locked on the exit.
427 */
428void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
429{
430 int lid = ipcid_to_idx(ipcp->id);
431
432 idr_remove(&ids->ipcs_idr, lid);
433 ids->in_use--;
434 ipcp->deleted = true;
435}
436
437/**
438 * ipc_alloc - allocate ipc space
439 * @size: size desired
440 *
441 * Allocate memory from the appropriate pools and return a pointer to it.
442 * NULL is returned if the allocation fails
443 */
444void *ipc_alloc(int size)
445{
446 void *out;
447 if (size > PAGE_SIZE)
448 out = vmalloc(size);
449 else
450 out = kmalloc(size, GFP_KERNEL);
451 return out;
452}
453
454/**
455 * ipc_free - free ipc space
456 * @ptr: pointer returned by ipc_alloc
457 * @size: size of block
458 *
459 * Free a block created with ipc_alloc(). The caller must know the size
460 * used in the allocation call.
461 */
462void ipc_free(void *ptr, int size)
463{
464 if (size > PAGE_SIZE)
465 vfree(ptr);
466 else
467 kfree(ptr);
468}
469
470/**
471 * ipc_rcu_alloc - allocate ipc and rcu space
472 * @size: size desired
473 *
474 * Allocate memory for the rcu header structure + the object.
475 * Returns the pointer to the object or NULL upon failure.
476 */
477void *ipc_rcu_alloc(int size)
478{
479 /*
480 * We prepend the allocation with the rcu struct
481 */
482 struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size);
483 if (unlikely(!out))
484 return NULL;
485 atomic_set(&out->refcount, 1);
486 return out + 1;
487}
488
489int ipc_rcu_getref(void *ptr)
490{
491 struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
492
493 return atomic_inc_not_zero(&p->refcount);
494}
495
496void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head))
497{
498 struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
499
500 if (!atomic_dec_and_test(&p->refcount))
501 return;
502
503 call_rcu(&p->rcu, func);
504}
505
506void ipc_rcu_free(struct rcu_head *head)
507{
508 struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
509
510 if (is_vmalloc_addr(p))
511 vfree(p);
512 else
513 kfree(p);
514}
515
516/**
517 * ipcperms - check ipc permissions
518 * @ns: ipc namespace
519 * @ipcp: ipc permission set
520 * @flag: desired permission set
521 *
522 * Check user, group, other permissions for access
523 * to ipc resources. return 0 if allowed
524 *
525 * @flag will most probably be 0 or S_...UGO from <linux/stat.h>
526 */
527int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
528{
529 kuid_t euid = current_euid();
530 int requested_mode, granted_mode;
531
532 audit_ipc_obj(ipcp);
533 requested_mode = (flag >> 6) | (flag >> 3) | flag;
534 granted_mode = ipcp->mode;
535 if (uid_eq(euid, ipcp->cuid) ||
536 uid_eq(euid, ipcp->uid))
537 granted_mode >>= 6;
538 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
539 granted_mode >>= 3;
540 /* is there some bit set in requested_mode but not in granted_mode? */
541 if ((requested_mode & ~granted_mode & 0007) &&
542 !ns_capable(ns->user_ns, CAP_IPC_OWNER))
543 return -1;
544
545 return security_ipc_permission(ipcp, flag);
546}
547
548/*
549 * Functions to convert between the kern_ipc_perm structure and the
550 * old/new ipc_perm structures
551 */
552
553/**
554 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
555 * @in: kernel permissions
556 * @out: new style ipc permissions
557 *
558 * Turn the kernel object @in into a set of permissions descriptions
559 * for returning to userspace (@out).
560 */
561void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
562{
563 out->key = in->key;
564 out->uid = from_kuid_munged(current_user_ns(), in->uid);
565 out->gid = from_kgid_munged(current_user_ns(), in->gid);
566 out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
567 out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
568 out->mode = in->mode;
569 out->seq = in->seq;
570}
571
572/**
573 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
574 * @in: new style ipc permissions
575 * @out: old style ipc permissions
576 *
577 * Turn the new style permissions object @in into a compatibility
578 * object and store it into the @out pointer.
579 */
580void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
581{
582 out->key = in->key;
583 SET_UID(out->uid, in->uid);
584 SET_GID(out->gid, in->gid);
585 SET_UID(out->cuid, in->cuid);
586 SET_GID(out->cgid, in->cgid);
587 out->mode = in->mode;
588 out->seq = in->seq;
589}
590
591/**
592 * ipc_obtain_object
593 * @ids: ipc identifier set
594 * @id: ipc id to look for
595 *
596 * Look for an id in the ipc ids idr and return associated ipc object.
597 *
598 * Call inside the RCU critical section.
599 * The ipc object is *not* locked on exit.
600 */
601struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id)
602{
603 struct kern_ipc_perm *out;
604 int lid = ipcid_to_idx(id);
605
606 out = idr_find(&ids->ipcs_idr, lid);
607 if (!out)
608 return ERR_PTR(-EINVAL);
609
610 return out;
611}
612
613/**
614 * ipc_lock - lock an ipc structure without rwsem held
615 * @ids: ipc identifier set
616 * @id: ipc id to look for
617 *
618 * Look for an id in the ipc ids idr and lock the associated ipc object.
619 *
620 * The ipc object is locked on successful exit.
621 */
622struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
623{
624 struct kern_ipc_perm *out;
625
626 rcu_read_lock();
627 out = ipc_obtain_object(ids, id);
628 if (IS_ERR(out))
629 goto err1;
630
631 spin_lock(&out->lock);
632
633 /* ipc_rmid() may have already freed the ID while ipc_lock
634 * was spinning: here verify that the structure is still valid
635 */
636 if (ipc_valid_object(out))
637 return out;
638
639 spin_unlock(&out->lock);
640 out = ERR_PTR(-EINVAL);
641err1:
642 rcu_read_unlock();
643 return out;
644}
645
646/**
647 * ipc_obtain_object_check
648 * @ids: ipc identifier set
649 * @id: ipc id to look for
650 *
651 * Similar to ipc_obtain_object() but also checks
652 * the ipc object reference counter.
653 *
654 * Call inside the RCU critical section.
655 * The ipc object is *not* locked on exit.
656 */
657struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
658{
659 struct kern_ipc_perm *out = ipc_obtain_object(ids, id);
660
661 if (IS_ERR(out))
662 goto out;
663
664 if (ipc_checkid(out, id))
665 return ERR_PTR(-EIDRM);
666out:
667 return out;
668}
669
670/**
671 * ipcget - Common sys_*get() code
672 * @ns: namsepace
673 * @ids: ipc identifier set
674 * @ops: operations to be called on ipc object creation, permission checks
675 * and further checks
676 * @params: the parameters needed by the previous operations.
677 *
678 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
679 */
680int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
681 struct ipc_ops *ops, struct ipc_params *params)
682{
683 if (params->key == IPC_PRIVATE)
684 return ipcget_new(ns, ids, ops, params);
685 else
686 return ipcget_public(ns, ids, ops, params);
687}
688
689/**
690 * ipc_update_perm - update the permissions of an ipc object
691 * @in: the permission given as input.
692 * @out: the permission of the ipc to set.
693 */
694int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
695{
696 kuid_t uid = make_kuid(current_user_ns(), in->uid);
697 kgid_t gid = make_kgid(current_user_ns(), in->gid);
698 if (!uid_valid(uid) || !gid_valid(gid))
699 return -EINVAL;
700
701 out->uid = uid;
702 out->gid = gid;
703 out->mode = (out->mode & ~S_IRWXUGO)
704 | (in->mode & S_IRWXUGO);
705
706 return 0;
707}
708
709/**
710 * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
711 * @ns: ipc namespace
712 * @ids: the table of ids where to look for the ipc
713 * @id: the id of the ipc to retrieve
714 * @cmd: the cmd to check
715 * @perm: the permission to set
716 * @extra_perm: one extra permission parameter used by msq
717 *
718 * This function does some common audit and permissions check for some IPC_XXX
719 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
720 * It must be called without any lock held and
721 * - retrieves the ipc with the given id in the given table.
722 * - performs some audit and permission check, depending on the given cmd
723 * - returns a pointer to the ipc object or otherwise, the corresponding error.
724 *
725 * Call holding the both the rwsem and the rcu read lock.
726 */
727struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
728 struct ipc_ids *ids, int id, int cmd,
729 struct ipc64_perm *perm, int extra_perm)
730{
731 kuid_t euid;
732 int err = -EPERM;
733 struct kern_ipc_perm *ipcp;
734
735 ipcp = ipc_obtain_object_check(ids, id);
736 if (IS_ERR(ipcp)) {
737 err = PTR_ERR(ipcp);
738 goto err;
739 }
740
741 audit_ipc_obj(ipcp);
742 if (cmd == IPC_SET)
743 audit_ipc_set_perm(extra_perm, perm->uid,
744 perm->gid, perm->mode);
745
746 euid = current_euid();
747 if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
748 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
749 return ipcp; /* successful lookup */
750err:
751 return ERR_PTR(err);
752}
753
754#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
755
756
757/**
758 * ipc_parse_version - ipc call version
759 * @cmd: pointer to command
760 *
761 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
762 * The @cmd value is turned from an encoding command and version into
763 * just the command code.
764 */
765int ipc_parse_version(int *cmd)
766{
767 if (*cmd & IPC_64) {
768 *cmd ^= IPC_64;
769 return IPC_64;
770 } else {
771 return IPC_OLD;
772 }
773}
774
775#endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
776
777#ifdef CONFIG_PROC_FS
778struct ipc_proc_iter {
779 struct ipc_namespace *ns;
780 struct ipc_proc_iface *iface;
781};
782
783/*
784 * This routine locks the ipc structure found at least at position pos.
785 */
786static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
787 loff_t *new_pos)
788{
789 struct kern_ipc_perm *ipc;
790 int total, id;
791
792 total = 0;
793 for (id = 0; id < pos && total < ids->in_use; id++) {
794 ipc = idr_find(&ids->ipcs_idr, id);
795 if (ipc != NULL)
796 total++;
797 }
798
799 if (total >= ids->in_use)
800 return NULL;
801
802 for (; pos < IPCMNI; pos++) {
803 ipc = idr_find(&ids->ipcs_idr, pos);
804 if (ipc != NULL) {
805 *new_pos = pos + 1;
806 rcu_read_lock();
807 ipc_lock_object(ipc);
808 return ipc;
809 }
810 }
811
812 /* Out of range - return NULL to terminate iteration */
813 return NULL;
814}
815
816static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
817{
818 struct ipc_proc_iter *iter = s->private;
819 struct ipc_proc_iface *iface = iter->iface;
820 struct kern_ipc_perm *ipc = it;
821
822 /* If we had an ipc id locked before, unlock it */
823 if (ipc && ipc != SEQ_START_TOKEN)
824 ipc_unlock(ipc);
825
826 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
827}
828
829/*
830 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
831 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
832 */
833static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
834{
835 struct ipc_proc_iter *iter = s->private;
836 struct ipc_proc_iface *iface = iter->iface;
837 struct ipc_ids *ids;
838
839 ids = &iter->ns->ids[iface->ids];
840
841 /*
842 * Take the lock - this will be released by the corresponding
843 * call to stop().
844 */
845 down_read(&ids->rwsem);
846
847 /* pos < 0 is invalid */
848 if (*pos < 0)
849 return NULL;
850
851 /* pos == 0 means header */
852 if (*pos == 0)
853 return SEQ_START_TOKEN;
854
855 /* Find the (pos-1)th ipc */
856 return sysvipc_find_ipc(ids, *pos - 1, pos);
857}
858
859static void sysvipc_proc_stop(struct seq_file *s, void *it)
860{
861 struct kern_ipc_perm *ipc = it;
862 struct ipc_proc_iter *iter = s->private;
863 struct ipc_proc_iface *iface = iter->iface;
864 struct ipc_ids *ids;
865
866 /* If we had a locked structure, release it */
867 if (ipc && ipc != SEQ_START_TOKEN)
868 ipc_unlock(ipc);
869
870 ids = &iter->ns->ids[iface->ids];
871 /* Release the lock we took in start() */
872 up_read(&ids->rwsem);
873}
874
875static int sysvipc_proc_show(struct seq_file *s, void *it)
876{
877 struct ipc_proc_iter *iter = s->private;
878 struct ipc_proc_iface *iface = iter->iface;
879
880 if (it == SEQ_START_TOKEN)
881 return seq_puts(s, iface->header);
882
883 return iface->show(s, it);
884}
885
886static const struct seq_operations sysvipc_proc_seqops = {
887 .start = sysvipc_proc_start,
888 .stop = sysvipc_proc_stop,
889 .next = sysvipc_proc_next,
890 .show = sysvipc_proc_show,
891};
892
893static int sysvipc_proc_open(struct inode *inode, struct file *file)
894{
895 int ret;
896 struct seq_file *seq;
897 struct ipc_proc_iter *iter;
898
899 ret = -ENOMEM;
900 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
901 if (!iter)
902 goto out;
903
904 ret = seq_open(file, &sysvipc_proc_seqops);
905 if (ret) {
906 kfree(iter);
907 goto out;
908 }
909
910 seq = file->private_data;
911 seq->private = iter;
912
913 iter->iface = PDE_DATA(inode);
914 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
915out:
916 return ret;
917}
918
919static int sysvipc_proc_release(struct inode *inode, struct file *file)
920{
921 struct seq_file *seq = file->private_data;
922 struct ipc_proc_iter *iter = seq->private;
923 put_ipc_ns(iter->ns);
924 return seq_release_private(inode, file);
925}
926
927static const struct file_operations sysvipc_proc_fops = {
928 .open = sysvipc_proc_open,
929 .read = seq_read,
930 .llseek = seq_lseek,
931 .release = sysvipc_proc_release,
932};
933#endif /* CONFIG_PROC_FS */